P167F

[Aaron]

I would also think with less power/torque output the engine emissions would also be different, as well, possibly not requiring as much heat, or producing more/less emissions depending on load/speed/etc.

 

This kinda makes sense in my head, but it may not make too much sense to someone reading this on the other end of the 'puter.

[Aaron]

Originally Posted By: Aaron

I didn't fail the test, for the record. I just got the two questions wrong about the order of aftertreatment components.

And thats only because you couldn't read my writing

I think I fucked up and mixed up which one you wrote down, cab & chassis/pickup.

[jimmy57]

Above a certain GVW, emissions certification has to be done via engine dynamometer since it is considered a "heavy duty" application.

 

Below that GVW, OEMs have the choice of certifying it as "light duty", which is done via chassis dynamometer.

 

The EPA cycles for the light duty vs heavy duty are very different. The light duty spends more time at lighter loads. That way, The OEMs can calibrate for high power and torque numbers without worrying so much about emissions.

Thanks, that does explain some things!

After working for a manufacturer for a long time I still see cost before anything thinking as basis for too many things.